Lubricating oil containing trithione-soxides as antioxidants



United States Patent 9 1 3,376,225 LUBRICATING OIL CONTAINING TRITHIONE-S- OXIDES'IAS ANTIOXIDANTS. Donald J. AndersomSan Anselmo, Calif., assignor to Chevron Research Company, San Francisco, Calif., a corporation of Delaware p v No Drawing. Filed June 6, 1966, Ser, No. 555,245 5 Claims. (Cl. 252-481) This-invention concerns. novel lubricating oil compositions having sulfur containing antioxidants.

Trithiones are .well known to Trithione compositions have been repeatedly reported in the literature. See for-example*U.S.-Paitent No. 2,995,569.

S C=SO S wherein R and R are hydrogen or hydrocarbyl (hydrocarbyl is a monovalent organic radical composed solely of carbon and hydrogen which may be aliphatic, alicyclic or aromatic, or combinations thereof, e.g., aralkyl), usually aliphatic hydrocarbyl, of a total of l to 22 carbon atoms, when other than hydrogen. Most usually, R and R will be alkyl of from about 1 to 8 carbon atoms, more usually of from about 1 to 6 carbon atoms.

The S-oxy trithione compositions can be prepared according to the methods disclosed in the art. Most conveniently, an olefin having the following functionality HC I=CCHa is contacted with sulfur at an elevated temperature, usually in excess of 175 C. and generally less than 275 C. for periods ranging from about 2 to 24 hours. The trithione compound may then be directly isolated.

The oxy derivative may then be prepared by dissolving the trithione in a suitable inert solvent, e.g., benzene, followed by the addition of hydrogen peroxide at ambient temperatures in the presence of a hydroxylic organic solvent, e.g., methanol, acetic acid, etc.

Olefins which find use in the preparation of the trithione are isobutylene, diisobutylene, triisobutylene, tetraisobutylene, 2-methyl-2-butene, 2,4,4-dirnethylpentene, etc.

The trithiones may also be prepared from compounds having functionalities other than olefinic, e.g., ketonic.

See Landis, Chem. Rev., 65 237 (1965).

The S-oxy trithione may be included in various lubricating media, i.e., oils and greases. The lubricating fluids which may be used with the compounds of this invention (hereinafter referred to as oils) may be derived from natural or synthetic sources. Oils generally have viscosities of from about 35 to 50,000 Saybolt Universal seconds (SUS) at 100 F. Among natural hydrocarbonaceous oils are paraffin base, naphthenic base, asphaltic base and mxied base oils. Illustrative synthetic oils are: hydrocarbon oils, such as polymer of various olefins, genearlly of from 2 to 8 carbon atoms, and alkylated aromatic hydrocarbons; and nonhydrocarbon oils, such as polyalkylene oxides, aromatic ethers, carboxylate esters, phosphate esters and silicon esters. The preferred media are the hydrocarbonaceous media, both natural and synthetic.

The above oils may be used individually or together, whenever miscible or made so by the use of mutual solvents.

have antioxidant activity.-

Otheradditives may also-be present such as :detergents, extreme pressure agents, grease thickeners, dyes,.oiliness" agents, corrosion inhibitors, etc.

The following example is offered by way of illustration and not by way of limitation.

EXAMPLE K Into a reaction flask was introduced 48.55 g. (0.19 mole) of 4-neopentyl-5-t.-butyl-1,2-dithiole-3-thione, 200 ml.of 'methanoland 25 'ml. ofethyl etheriTothis mix ture was slowly added 21.2 g. (0.19'mo1e) of 30% aqueous hydrogen peroxide in ml. of methanol. During the addition the temperature was maintained between 35 and 40 C. When the addition was completed, the reaction mixture was refluxed for 1 hour. At the end of this time, the reaction mixture was transferred to a separatory funnel, diluted with 250 ml. of water and extracted 3 times with m1. fractions of diethyl ether. The combined ether fractions were dried and the ether distilled off. The residue weighed 41.92 g. After standing overnight, the residue crystallized and was recrystallized in an ether pentane solution. Melting point 83-35" C. An infrared spectrum was consistent wtih the S-oxy 4- neopentyl-5-t.-butyl-1,2-dithiole-3-thione structure.

In order to demonstrate the effectiveness as an antioxidant of the S-oxy trithione, the following test was carried out. To 25 g. of a Mid-Continent SAE 30 oil was added 0.2 cc. of a solution having 3,160 ppm. of copper, 2,670 ppm. of iron, p.p.m. of manganese, 36,700 p.p.m. of lead and 1,631 p.p.m. of tin, all as their naphthenates, providing a distribution of metals which would be expected to be found in used crankcase oils after an L-4 Chevrolet engine test. The oil sample to be tested is maintained at 340 F. and the time required to absorb 250 ml. of oxygen is observed. The results are reported as if 100 g. was used and 1,000 ml. of oxygen absorbed. Without the additive, the oxygen was absorbed in 0.12 hour, while with the additive the time required was 3.21 hours.

In order to demonstrate the significant decrease in copper corrosion, the following test was carried out. A clean copper strip 1" x 3" x g" thickness is immersed in 300 ml. of a Mid-Continent SAE 30 oil and held in the oil at 340 F. for 20 hours, while the oil is stirred with a stirrer rotating at 800 rpm. The strip is then removed, washed with hexanes, allowed to dry and weighed. The strip is then washed with a potassium cyanide solution (40 g. of potassium cyanide in 160 ml. of water), rinsed with water, then acetone, allowed to dry and reweighed. The potassium cyanide removes any scale which may be present.

Two samples were prepared, one containing 0.5 weight percent of 4 neopentyl-5-t.-butyl-1,2 dithiole-3-thione and the other containing 0.5 weight percent of the S-oxy derivative of the same trithione, and a third sample without additive used as a control. The following table indicates the results:

TAB LE I Copper Weight Loss (mg) Before KCN After KCN Trithione 342 365 S-oxy trithione 18. 6 25. 7 No additive 124 128 will generally range from- As will be evident to those skilled in the art, various modifications on this invention can be made or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the following claims.

I claim:

1. A lubricating oil composition containing in an amount sufiicient for antioxidation a corn-position of the formula:

wherein R and R are hydrogen or hydrocarbyl having a total of from 1 to 22 carbon atoms.

2. A composition according to claim 1, wherein R and R when other than hydrogen, are aliphatic.

3. A composition according to claim 1, wherein R and R are alkyl of from about 1 to 8 carbon atoms.

5 4. A composition according to claim 1, wherein R is neopentyl and R is tert.-butyl.

5. A composition according to claim 1, wherein said amount is in the range of 0.1 to 5 weight percent.

References Cited UNITED STATES PATENTS 2,816,075 12/1957 Fields 252-45 2,995,569 8/1961 Hamilton et al. 252406 XR 15 DANIEL E. WYMAN, Primary Examiner.

W. H. CANNON, Assistant Examiner. 

1. A LUBRICATING OIL COMPOSITION CONTAINING IN AN AMOUNT SUFFICIENT FOR ANTIOXIDATION A COMPOSITION OF THE FORMULA: 